Fig. 1.

ISC-4 reduces cell viability more potently than other Akt inhibitors. A, structure of ISC-4. B, HT29 cells were treated for 48 hours with increasing concentrations of Akt inhibitors, or with DMSO vehicle. ISC-4 was significantly more potent than were API2 and PBITC at doses of 12.5 and 25 µM. Both PBITC and ISC-4 compounds were more potent than API2 at 50 µM (p=0.000585). The table depicts IC₅₀ values of compounds from MTT assay. C, A panel of colon cancer cell lines was treated with increasing concentrations of ISC-4. Data show a dose dependent response in each cell line. All cells were dead at 50 µM ISC-4. The Western blot analysis shows Par-4 and phosphoAkt (pAkt) protein expression in all cell lines. The upper band in the pAkt lane represents Akt1, the isoform responsible for Par-4 inhibition. D, ISC-4 treatment of wild type or Par-4 transfected cells with increasing doses of ISC-4 or DMSO vehicle for 48 hours showed that mock transfected cells and cells transfected with rat par-4 were less sensitive to treatment than were human Par-4 transfected cells (clones 12 and 17) (p=0.014177 - overall treatment effect). Compare Par-4 transfected cells to Mock transfected cells at specific dose levels (hPar-4 cl 12, p=0.0304 and 0.015, hPar-4 cl 17, p=0.0014 and 0.0038 for 6.25 µM and 12.5 µM ISC-4, respectively). Asterisks indicate cells with significantly increased sensitivity to ISC-4 over Mock transfected cells.